ORAU Team

Dose Reconstruction Project for NIOSH

External Coworker Dosimetry Data for the Hanford Site

Document Number:

ORAUT-OTIB-0030

Effective Date: 03/23/2005

Revision No.: 00

Controlled Copy No.: ______

Page 1 of 8

Subject Expert: Steven E. Merwin

Document Owner

Approval: Signature on File Date: 03/10/2005

Edward F. Maher, Task 5 Manager

Concurrence: Signature on File Date: 03/11/2005

Richard E. Toohey, Project Director

Approval: Signature on File Date: 03/23/2005

James W. Neton, Associate Director for Science

Supersedes:

None
Effective Date: 03/23/2005 Revision No.: 00 Document No. ORAUT-OTIB-0030 Page 2 of 8

RECORD OF ISSUE/REVISIONS

ISSUE 

AUTHORIZATION 

DATE

EFFECTIVE 

DATE

REV. 

NO. DESCRIPTION

Draft 01/24/2005 00-A New technical information bulletin to provide 

information to allow ORAU Team dose 

reconstructors to assign doses to certain workers 

at the Hanford site who have no or limited 

monitoring data, based on site coworker data. 

Initiated by Steven E. Merwin.

Draft 02/02/2005 00-B Incorporates additional information. Initiated by 

Steven E. Merwin.

Draft 02/25/2005 00-C Incorporates responses to NIOSH comments. 

Initiated by Steven E. Merwin.

03/23/2005 03/23/2005 00 First approved issue. Initiated by Steven E. 

Merwin.
Effective Date: 03/23/2005 Revision No.: 00 Document No. ORAUT-OTIB-0030 Page 3 of 8

1.0 PURPOSE

The purpose of this Technical Information Bulletin (TIB) is to provide information to allow ORAU Team 

dose reconstructors to assign doses to workers at the Hanford Site who have no or limited monitoring 

data, based on site coworker data. The data in this TIB are to be used in conjunction with ORAUTOTIB-0020, “Use of Coworker Dosimetry Data for External Dose Assignment.”

1

2.0 BACKGROUND

The ORAU Team is conducting a series of coworker data studies to permit dose reconstructors to 

complete certain cases for which external and/or internal monitoring data are unavailable or 

incomplete. Cases not having complete monitoring data may fall into one of several categories, 

including:

• The worker was unmonitored and, even by today’s standards, did not need to be monitored 

(e.g., a non-radiological worker).

• The worker was unmonitored, but by today’s standards would have been monitored.

• The worker may have been monitored but the data are not available to the dose reconstructor.

• The worker may have partial information, but the available information is insufficient to permit 

a dose reconstruction to occur.

As described in ORAUT-OTIB-0020, some cases not having complete monitoring data can be 

processed based on assumptions and methodologies that do not involve coworker data. For 

example, many cases falling in the first category above can be processed by assigning ambient 

external and internal doses based on information in the relevant site Technical Basis Documents 

(TBDs).

As described in the Hanford External Dosimetry TBD,2 Hanford began operations in 1944 using inhouse dosimeter and processing technical support. Routine Hanford practices appear to have 

required assigning dosimeters to all workers who entered a controlled radiation area. The trends in 

the number of workers who were monitored, the number of monitored workers with positive recorded 

dose, and the collective dose do not show any abrupt changes that may be indicative of significant 

changes in photon dosimetry or assignment of dosimeters.2 Additionally, there does not appear to be 

any significant administrative practice that would jeopardize the integrity of the recorded dose of

record.

3.0 GENERAL APPROACH

As described in ORAUT-OTIB-0020,1 the general approach to developing coworker data for cases 

without external monitoring data involves two phases. The first phase (Phase I) permits cases to be 

processed when a “best and final” estimate of dose is not required for claim determination. The 

second phase (Phase II) facilitates the assignment of “best and final estimates” of dose, when 

necessary. This initial revision of this TIB provides coworker external dosimetry summary statistics 

applicable to Phase I dose reconstructions; coworker dose distributions applicable to Phase II dose 

reconstructions will be made available in a subsequent revision. 
Effective Date: 03/23/2005 Revision No.: 00 Document No. ORAUT-OTIB-0030 Page 4 of 8

4.0 APPLICATIONS AND LIMITATIONS

1. Revision 0 of this document provides Hanford site coworker data and information that may be 

used only for clearly non-compensable cases for which a higher external dose can be assigned 

than was likely to have been actually received. Revision 1 of this document will provide dose 

distributions and additional information based on the data presented herein to permit the 

processing of clearly compensable cases or cases requiring a best estimate analysis.

2. Some Hanford Site workers may have worked at one or more other major sites within the DOE 

complex during their employment history. Thus, the data presented herein must be used with 

caution to ensure that for clearly non-compensable, unmonitored external doses from multiple site 

employment have been overestimated. This will typically require the availability of External 

Coworker Dosimetry Data TIBs for all relevant sites.

3. Summary statistics based on Hanford dosimetry data presented in this TIB do not extend beyond 

1989 because at the time this TIB was drafted, data beyond 1989 were not available from the 

Comprehensive Epidemiologic Data Resource (CEDR). However, the absence of these data (and 

the subsequent development of dose distributions) should not interfere with the processing of 

most Hanford cases having a lack of external dosimetry data since well before 1989 the

monitoring and reporting practices at the site ensured that essentially all workers with a potential 

for external radiation exposure were monitored and the results are readily accessible. Should the 

need arise and sufficient data become available, coworker dosimetry data beyond the year 1989

will be presented in a subsequent revision to this TIB.

4. The data presented in this TIB address penetrating radiation from gamma radiation and nonpenetrating radiation from beta radiation (or low-energy photons for work involving Pu). Neutron 

data are not presented. However, the locations within the Hanford site at which neutron 

exposures were possible are limited to certain site areas and facilities, and the site TBD 

establishes a method for assigning neutron doses when relevant.2 Therefore, the TBD should be 

used as the basis for assigning neutron doses, when relevant, in addition to the photon and/or 

beta doses assigned in accordance with this TIB.

5. For the years 1972 and later, external on-site ambient doses should not be included in addition to 

the co-worker doses assigned in accordance with this TIB, because any such doses would have 

been included in the dosimetry results reported by the site which were used as the basis for the 

coworker dose distributions presented below.

2

 Prior to 1972, co-worker doses assigned in 

accordance with this TIB must be supplemented by the appropriate external on-site ambient dose 

in accordance with the instructions in ORAUT-PROC-0060.4

5.0 REFERENCES

1. ORAU Team, ORAUT-OTIB-0020, Use of Coworker Dosimetry Data for External Dose 

Assignment, Rev 00, December 29, 2004

2. ORAU Team, ORAUT-TKBS-0006-6, Technical Basis Document for the Hanford Site –

Occupational External Dose, Rev 01, January 9, 2004.

3. NIOSH (National Institute for Occupational Safety and Health), External Dose Reconstruction 

Implementation Guideline, Rev. 0, OCAS-IG-001, Office of Compensation Analysis and Support, 

Cincinnati, Ohio, 2002.
Effective Date: 03/23/2005 Revision No.: 00 Document No. ORAUT-OTIB-0030 Page 5 of 8

4. ORAU Team, ORAUT-PROC-0060, External On-Site Ambient Dose Reconstruction for DOE 

Sites, Rev 00, January 31, 2005.

5. ORAU Team, ORAUT-OTIB-0017, Interpretation of Dosimetry Data for Assignment of Shallow 

Dose, Rev 00, January 11, 2005.

6.0 HANFORD COWORKER DATA DEVELOPMENT

Dosimetry data for monitored Hanford workers from the CEDR databases maintained by the U.S. 

Department of Energy (DOE) were selected for this evaluation. The CEDR data evaluated 

represented primarily annual penetrating and non-penetrating dosimetry data provided by the Hanford

site, which pertain to the shielded and “open-window minus shielded” dosimetry readings, 

respectively, and exclude neutron doses. Starting in 1982, multiple badge readings are recorded in 

CEDR for some Hanford workers; however, this was a relatively small fraction of the total, and the 

adjustments made for partial years of employment (see Section 7) are likely to account for any data 

that do not encompass a full year. Also, starting in 1983 the CEDR data included the reported 

shallow dose, not the non-penetrating dose. Thus, for these years, the non-penetrating doses were 

derived by subtracting the reported penetrating doses from the reported shallow doses.

Between 1957 and 1971, the Hanford Site film dosimeter included a third measurement (in addition to 

the standard shielded and open-window measurement) using a special filter covering a portion of the 

film designed to allow the assessment of X-ray doses. Thus, doses in this time period were reported 

as beta, gamma, and X-ray. A fraction (0.65) of the X-ray dose was assumed to contribute to nonpenetrating dose, and the remainder (0.35) was assumed to contribute to penetrating dose. Since the 

CEDR data include the X-ray doses reported by the site for this period, the coworker dose evaluations 

described in this TIB include an upward adjustment of the reported beta and gamma doses during this 

period by adding 65% and 35% of the reported X-ray doses, respectively, to arrive at the reported 

non-penetrating and penetrating doses. 

The validity of the CEDR data was confirmed by selecting a sampling of claimant dosimetry data 

submitted by the site as part of the EEOICPA Subtitle B program and comparing it to the pertinent 

CEDR data. A review of annual data for ten claimants covering 297 worker-years of employment at 

Hanford indicated excellent agreement between the two data sets. Specifically, the reported 

penetrating and non-penetrating data in the CEDR database were found to correspond to the reported 

external and “skin minus external” annual doses reported in the site Radiological Exposure System. It 

is concluded that the CEDR data are acceptable for the development of coworker doses for the 

Hanford Site, with adjustments made for the reported X-ray doses as appropriate, as described 

above.

Adjustment for Missed Dose

According to the External Dose Reconstruction Implementation Guideline,3 missed doses are to be 

assigned for null dosimeter readings to account for the possibility that doses were received but not 

recorded by the dosimeter or reported by the site. Annual missed doses are calculated by multiplying 

the number of null badge readings by the dosimeter limit of detection (LOD) and summing the results. 

These values are used as the 95th percentile of a lognormal distribution for the purpose of calculating 

probability of causation; thus, in IREP the calculated missed doses are multiplied by 0.5 and entered 

in Parameter 1, and a value of 1.52 is entered in Parameter 2, to represent the geometric mean and 

geometric standard deviation, respectively.

The assignment of missed doses for monitored workers is particularly significant for Hanford

claimants prior to 1951 when workers were monitored weekly, and between 1951 and 1957 when 
Effective Date: 03/23/2005 Revision No.: 00 Document No. ORAUT-OTIB-0030 Page 6 of 8

workers were monitored biweekly. Table 1 lists the maximum annual missed dose by era and type of 

radiation (penetrating gamma and non-penetrating) based on information presented in the site TBD2

and ORAUT-OTIB-0017.5

Table 1. Missed external doses based on Hanford Occupational External Dosimetry TBD2 and 

ORAUT-OTIB-0017.

5

Maximum annual missed dose (rem)

Period

Penetrating 

LOD (rem)

Non-penetrating 

LOD (rem)a

Exchange 

frequency Penetrating Non-penetrating

1944

a

-1950 0.04 0.05 Weekly 2.080 2.600

1951-1956 0.04 0.05 Biweekly 1.040 1.300

1957 0.04 0.05 Variedb0.720 0.900

1958-1971 0.04 0.05 Monthly 0.480 0.600

1972-1994 0.02 0.03 Monthlyc0.240 0.360

1994-present 0.01 0.05 Monthlyc0.120 0.600

a. Hanford instituted a weekly exchange and the use of film dosimeters in October 1944.

b. The exchange frequency was biweekly through May 1957, then monthly. A total of 18 exchanges was assumed for the 

year.

c. The TBD indicates that either monthly or quarterly exchange frequencies were used. Monthly exchanges have been 

assumed here to ensure claimant favorability.

Special Considerations

Certain aspects of the external dosimetry practices at the Hanford Site documented in the TBD2 were 

considered in the analysis of the site data. These include:

• In some cases, values less than the dosimeter LOD were reported by the site. For example, 

values as low as 10 or 20 mR were reported even though the penetrating LOD was considered 

to be 40 mrem (or 40 mR) prior to 1972.

• The data available to analyze coworker doses represent annual dose summaries for individual 

workers. Because these data include partial work years, the average annual doses reported 

tend to underestimate the average annual doses received by employees who worked an entire 

year. 

As described in Section 7.0 below, a claimant-favorable approach was adopted in the development of 

coworker dose summaries, and this approach should account for any underestimate of doses to 

radiological workers at the Hanford site based on the considerations described above.

7.0 HANFORD COWORKER ANNUAL DOSE SUMMARIES

Based on the information and approaches described above, Hanford coworker annual external 

dosimetry summaries were developed for use in the evaluation of external dose for certain claimants 

potentially exposed to workplace radiation, but with no or limited monitoring data provided by DOE. 

These summaries were developed using the following steps:

1. As described in Section 6.0 above, the penetrating and non-penetrating doses available from 

CEDR, which represented annual summary data, were modified to account for partial years of 

employment. This adjustment was made by analyzing the NOCTS employment data for Hanford 

workers and adjusting the reported doses upward by an appropriate multiplier corresponding to 

the average fraction of a year an employee worked at the site. For example, if in a particular 

calendar year the average employment period for all Hanford employees in NOCTS was 11 

months, the CEDR annual doses were multiplied by 12/11, or 1.09. This permits the dose 

reconstructor to assign an appropriate prorated dose to account for partial years of employment or 
Effective Date: 03/23/2005 Revision No.: 00 Document No. ORAUT-OTIB-0030 Page 7 of 8

potential exposure. A factor of 4 was applied for the year 1944 when monitoring at the site did not 

begin until October.

2. For the years 1957 through 1971, when X-ray doses were reported separately in addition to the 

reported gamma and beta doses, but were not included in the reported annual penetrating and 

non-penetrating doses, the penetrating and non-penetrating doses were modified by adding 35% 

and 65% of the reported positive X-ray doses, respectively.2,5

3. The 50th, 95th and 99th percentile annual penetrating and non-penetrating doses were derived for 

two scenarios: excluding and including reported zeroes.

4. The 50th, 95th and 99th percentile doses based on the exclusion of zeroes were used as the 

basis for the coworker data set, since these are representative of radiological worker doses which 

are the principal focus of the coworker studies. However, to ensure claimant favorability, for 

penetrating radiation the percentile doses with zero results included were evaluated, and if the 

addition of one-half of the maximum annual non-penetrating missed doses (listed in Table 1) to 

these percentile doses resulted in values exceeding the percentile doses based on the exclusion 

of zeroes, the latter were replaced with the former. Missed doses were not added to both the 

penetrating and non-penetrating results because the non-penetrating results reported by the site 

reflect the difference between the open-window and shielded measurements, and assigning 

missed dose to both measurements would result in a double counting since a positive shielded 

measurement exceeding the non-penetrating MDL would appear as a positive open-window 

measurement. To ensure claimant favorability, the non-penetrating MDLs were assigned in the 

calculations (since they exceed the penetrating MDLs), and the values were apportioned to the 

penetrating doses (since penetrating doses are assigned as gamma radiation, which in IREP 

cannot have a negative effect because the radiation effectiveness factors for gammas are equal to 

or greater than for >15 keV electrons.

5. The results are presented in Table 2 below. These percentile doses should be used for selected 

Hanford workers with no or limited monitoring data using the methodologies outlined in Section 7.0 

of ORAUT-OTIB-0020.1 Because the values include a claimant-favorable adjustment for potential 

missed dose, the 50th-percentile values should not be applied for cases with POCs >50%. Should 

these data prove insufficient for the completion of dose reconstructions, “best estimate” coworker

dose distributions should be used as documented in Section 8.0 below and in accordance with 

Section 8.0 of ORAUT-OTIB-0020.1

Doses to organs impacted only by penetrating radiation (e.g., organs other than the skin, breast and 

testes) are calculated based only on the “Gamma” columns in Table 2 combined with the appropriate 

organ dose conversion factors (DCFs).3 Doses to the skin, breast and testes (and any other cancer 

location potentially impacted by non-penetrating radiation) are determined based on both the 

“Gamma” and “Non-penetrating” columns; gamma doses are assigned as photons with an energy 

range consistent with information in the external dosimetry TBD for the Hanford site,2 and nonpenetrating doses are assigned as electrons >15 keV with corrections applied to account for clothing 

attenuation or other applicable considerations, or photons <30 keV, depending on the employment 

location and job description. 

8.0 HANFORD COWORKER ANNUAL DOSE DISTRIBUTIONS

Reserved
Effective Date: 03/23/2005 Revision No.: 00 Document No. ORAUT-OTIB-0030 Page 8 of 8

Table 2. Annual Hanford external coworker doses modified to 

account for missed dose (rem).

Year

Gamma

99th%

Gamma

95th%

Gamma

50th%

Non-pen

99th%

Non-pen

95th%

Non-pen

50th%

1944 3.096 2.176 1.300 3.363 1.448 0.240

1945 3.294 2.430 1.336 4.215 0.631 0.071

1946 2.917 2.125 1.448 5.944 1.421 0.297

1947 2.113 1.708 1.369 3.130 1.081 0.222

1948 1.805 1.541 1.334 5.400 1.096 0.149

1949 1.818 1.572 1.357 3.895 1.076 0.215

1950 2.107 1.721 1.357 3.222 1.535 0.239

1951 2.263 1.278 0.685 4.276 2.047 0.212

1952 2.504 1.541 0.721 2.782 1.046 0.155

1953 2.691 1.815 0.779 2.828 1.477 0.188

1954 3.053 1.863 0.720 2.438 1.260 0.175

1955 3.246 2.059 0.717 2.230 1.287 0.200

1956 3.344 2.306 0.682 2.262 1.189 0.141

1957 3.325 2.318 0.650 1.755 0.942 0.119

1958 3.236 2.599 0.321 1.326 0.695 0.074

1959 2.867 2.237 0.300 2.120 1.122 0.127

1960 3.276 2.756 0.311 2.622 1.419 0.162

1961 3.293 2.877 0.364 1.938 1.001 0.075

1962 3.406 3.018 0.452 1.695 0.805 0.108

1963 3.389 2.981 0.406 1.715 0.760 0.050

1964 3.437 3.018 0.505 1.954 0.690 0.042

1965 4.849 3.880 0.881 2.338 0.905 0.098

1966 3.574 2.690 0.524 1.881 0.841 0.056

1967 4.118 3.179 0.385 3.161 1.476 0.073

1968 3.473 2.801 0.436 2.253 0.890 0.084

1969 3.529 2.905 0.354 2.147 0.923 0.075

1970 3.689 3.159 0.323 2.623 1.267 0.092

1971 3.776 2.726 0.394 2.978 1.237 0.165

1972 3.458 2.339 0.293 1.060 0.565 0.090

1973 3.380 2.142 0.246 1.729 0.535 0.055

1974 3.473 2.099 0.283 1.253 0.513 0.068

1975 3.337 1.933 0.283 1.201 0.549 0.080

1976 3.091 1.667 0.226 0.741 0.359 0.069

1977 3.748 2.188 0.206 1.026 0.365 0.052

1978 2.934 1.252 0.214 0.530 0.237 0.034

1979 2.967 1.257 0.202 0.662 0.276 0.044

1980 2.658 0.968 0.203 0.551 0.293 0.045

1981 2.596 1.103 0.191 0.620 0.425 0.092

1982 2.980 1.432 0.191 0.533 0.329 0.057

1983 3.081 1.933 0.180 0.603 0.261 0.045

1984 2.785 1.643 0.191 0.723 0.321 0.034

1985 2.911 1.849 0.180 0.834 0.297 0.034

1986 2.851 1.985 0.180 0.714 0.312 0.022

1987 2.260 1.048 0.195 0.403 0.135 0.015

1988 0.360 0.236 0.180 0.101 0.045 0.011

1989 0.508 0.236 0.180 0.124 0.034 0.011